The preparation of a latex from certain polymers, such as butyl rubber and sulfobutyl rubber is known. Thus, aqueous suspensions of such materials have herebefore been prepared, employing various emulsifying agents and stabilizers, and latex products have been prepared from these emulsions for use as adhesives and as bonding agents for various fibers, etc. While such processes are known, the preparation of artificial latices, particularly from polymers containing acidic functionality, and their neutralized counterparts, has been difficult. These particular polymers, and their neutralized analogues, e.g., the sodium salts of sulfobutyl rubbers, are very difficult to emulsify. They require mixed solvent systems to effect solubilization, very specific emulsifiers, and are very susceptible to inversion to water in oil emulsions during finishing.
It is therefore an object of the present invention to provide a novel process for preparing latices of ionomeric polymers containing carboxylate functionality in a simple and uncomplicated manner.
In order better to understand the significance of this invention, however, it is necessary to review first the development of the polymers which form the base for this new latex.
Butyl rubber is produced by the copolymerization of an isoolefin such as isobutene with a conjugated multiolefin such as isoprene or butadiene. While butyl rubber has been a highly successful commercial product, various modified forms of butyl rubber containing greater degrees of unsaturation have been sought. Thus, Ser. No. 228,727, filed on Feb. 23, 1972 in the name of Francis P. Baldwin and Alberto Malatesta, now U.S. Pat. No. 3,816,371, and Ser. No. 228,728, also filed on Feb. 23, 1972 in the name of Francis P. Baldwin, now U.S. Pat. No. 3,775,387, respectively disclose a conjugated diene butyl rubber and a method for preparing same. These applications thus disclose the dehydrohalogenation of halogenated butyl rubber in order to produce a conjugated diene butyl rubber containing conjugated diene unsaturation. The conjugated diene butyl rubber thus produced, as described and claimed in Ser. No. 228,727, which is incorporated herein by reference, is represented by the general formula: ##EQU1## wherein n + 1 represents the number of isoolefin units incorporated in the butyl rubber, and m represents the number of initial diolefin units present, though other structures may be present, for example the structure: ##EQU2##
Further, several methods for preparing such conjugated diene butyl rubber are disclosed in Ser. No. 228,727, and these methods are also incorporated herein by reference. Additionally, other conjugated diene structures derivable from generic butyl rubber are disclosed in Ser. No. 465,479, filed on Apr. 30, 1974.
As stated above, it is therefore an object of the present invention to provide an uncomplicated method of preparing latices from such polymers and the resulting modified analogues occurring from the Diels-Alder addition of a dienophilic anhydride. It is another object of this invention to provide improved latices for use, in films, as adhesives, bonding agents, paper coatings, etc.